Relationships between health behaviors,posttraumatic stress disorder,and comorbid general anxiety and depression

Poor health outcomes associated with posttraumatic stress disorder (PTSD) may reflect engagement in unhealthy behaviors that increase morbidity risk and disengagement in healthy behaviors that decrease morbidity risk. Although research supports this pattern, findings are not definitive, particularly for healthy behaviors. Many studies have not controlled for effects of concurrent generalized anxiety and depression, which might explain conflicting findings. To address this limitation, we used an online cross-sectional research design and multivariate multilevel modelling to evaluate associations between a multitude of health behaviors (i.e. sedentary behavior, sleep quality, physical activity, eating habits, alcohol use and substance use) and PTSD, while adjusting for comorbid generalized anxiety and depression, in a sample of trauma-exposed individuals (N = 246). Our results indicate that PTSD and comorbid generalized anxiety and depression symptoms were differentially associated with specific health constructs. Specifically, sedentary behavior and poor sleep quality were associated with PTSD, whereas low physical activity, poor sleep quality, and unhealthy eating habits were associated with depression. Both increased alcohol and substance use were associated with generalized anxiety. Results from our study highlight the need to conceptualize associations between health behaviors and specific psychological symptoms in a comprehensive manner as part of clinical presentations of PTSD.     

Individuals Intolerant of Uncertainty: The Maintenance of Worry and Distress Despite Reduced Uncertainty

The intolerance of uncertainty model of worry posits that individuals worry as a means to cope with the discomfort they feel when outcomes are uncertain, but few experimental studies have investigated the causal relationships between intolerance of uncertainty, situational uncertainty, and state worry. Furthermore, existing studies have failed to control for the likelihood of future negative events occurring, introducing an important rival hypothesis to explain past findings. In the present study, we examined how individuals with high and low trait intolerance of uncertainty differ in their behavioral, cognitive, and emotional reactions to situational uncertainty about an upcoming negative event (watching emotionally upsetting film clips), holding constant the likelihood of that negative event taking place. We found that although individuals high in trait prospective intolerance of uncertainty reported a higher degree of belief that being provided with detailed information about the upcoming stressor would make them feel more at ease, they did not experience an actual decrease in distress or state worry upon being provided with more information, during anticipation of the film clips, or during the film clips themselves. Our results suggest that heightened distress regarding negative events may be more central than intolerance of uncertainty to the maintenance of worry.     

Poisson Multilevel Models with Small Samples

Recent methodological studies have investigated the properties of multilevel models with small samples. Previous work has primarily focused on continuous outcomes and little attention has been paid to count outcomes. The estimation of count outcome models can be difficult because the likelihood has no closed-form solution, meaning that approximation methods are required. Although adaptive Gaussian quadrature (AGQ) is generally seen as the gold standard, its comparative performance has been investigated with larger samples. AGQ approximates the full likelihood, a function that is known to produce biased estimates with small samples with continuous outcomes. Conversely, penalized quasi-likelihood (PQL) is considered to be a less desirable approximation; however, it can approximate the restricted likelihood function, a function that is known to perform well with smaller samples with continuous outcomes. The goal of this paper is to compare the small sample bias of full likelihood methods to the linearization bias of PQL with restricted likelihood. Simulation results indicate that the linearization bias of PQL is preferable to the finite sample bias of AGQ with smaller samples.     

Sensitivity and bias under conditions of equal and unequal academic task difficulty

We conducted an experimental analysis of children's relative problem-completion rates across two workstations under conditions of equal (Experiment 1) and unequal (Experiment 2) problem difficulty. Results were described using the generalized matching equation and were evaluated for degree of schedule versus stimulus control. Experiment 1 involved a symmetrical choice arrangement in which the children could earn points exchangeable for rewards contingent on correct math problem completion. Points were delivered according to signaled variable-interval schedules at each workstation. For 2 children, relative rates of problem completion appeared to have been controlled by the schedule requirements in effect and matched relative rates of reinforcement, with sensitivity values near 1 and bias values near 0. Experiment 2 involved increasing the difficulty of math problems at one of the workstations. Sensitivity values for all 3 participants were near 1, but a substantial increase in bias toward the easier math problems was observed. This bias was possibly associated with responding at the more difficult workstation coming under stimulus control rather than schedule control.     

Relative reinforcer rates and magnitudes do not control concurrent choice independently

One assumption of the matching approach to choice is that different independent variables control choice independently of each other. We tested this assumption for reinforcer rate and magnitude in an extensive parametric experiment. Five pigeons responded for food reinforcement on switching-key concurrent variable-interval variable-interval schedules. Across conditions, the ratios of reinforcer rates and of reinforcer magnitudes on the two alternatives were both manipulated. Control by each independent variable, as measured by generalized-matching sensitivity, changed significantly with the ratio of the other independent variable. Analyses taking the model-comparison approach, which weighs improvement in goodness-of-fit against increasing number of free parameters, were inconclusive. These analyses compared a model assuming constant sensitivity to magnitude across all reinforcer-rate ratios with two alternative models. One of those alternatives allowed sensitivity to magnitude to vary freely across reinforcer-rate ratios, and was less efficient than the common-sensitivity model for all pigeons, according to the Schwarz-Bayes information criterion. The second alternative model constrained sensitivity to magnitude to be equal for pairs of reinforcer-rate ratios that deviated from unity by proportionately equal amounts but in opposite directions. This model was more efficient than the common-magnitude-sensitivity model for 2 of the pigeons, but not for the other 3. An analysis of variance, carried out independently of the generalized-matching analysis, also showed a significant interaction between the effects of reinforcer rate and reinforcer magnitude on choice. On balance, these results suggest that the assumption of independence inherent in the matching approach cannot be maintained. Relative reinforcer rates and magnitudes do not control choice independently.     

Determinants of imitation of hand-to-body gestures in 2- and 3-year-old children

Twenty children, ten 2-year-olds and ten 3-year-olds, participated in an AB procedure. In the baseline phase, each child was trained the same four matching relations to criterion under intermittent reinforcement. During the subsequent imitation test, the experimenter modeled a total of 20 target gestures (six trials each) interspersed with intermittently reinforced baseline trials. In each session, target gestures were selected in a pre-randomized sequence from: Set 1--ear touches; Set 2--shoulder touches; Set 3--midarm touches; and Set 4--wrist touches; subjects' responses to targets were not reinforced. In each target set, half the gestures featured in nursery matching games and were termed common targets whereas the remainder, which were topographically similar but did not feature in the games, served as uncommon targets. The children produced significantly more matching responses to common target models than to uncommon ones. Common responses were also produced as mismatches to uncommon target models more often than vice versa. Response accuracy did not improve over trials, suggesting that "parity" did not serve as a conditioned reinforcer. All children showed a strong bias for "mirroring"--responding in the same hemispace as the modeler. The 2-year-olds produced more matching errors than the 3-year-olds and most children showed a bias for responding with their right hands. The strong effects of training environment (nursery matching games) are consistent with a Skinnerian account, but not a cognitive goal theory account, of imitation in young children.     

Regularized Partial and/or Constrained Redundancy Analysis

Methods of incorporating a ridge type of regularization into partial redundancy analysis (PRA), constrained redundancy analysis (CRA), and partial and constrained redundancy analysis (PCRA) were discussed. The usefulness of ridge estimation in reducing mean square error (MSE) has been recognized in multiple regression analysis for some time, especially when predictor variables are nearly collinear, and the ordinary least squares estimator is poorly determined. The ridge estimation method was extended to PRA, CRA, and PCRA, where the reduced rank ridge estimates of regression coefficients were obtained by minimizing the ridge least squares criterion. It was shown that in all cases they could be obtained in closed form for a fixed value of ridge parameter. An optimal value of the ridge parameter is found by G-fold cross validation. Illustrative examples were given to demonstrate the usefulness of the method in practical data analysis situations. We thank Jim Ramsay for his insightful comments on an earlier draft of this paper. The work reported in this paper is supported by Grants 10630 from the Natural Sciences and Engineering Research Council of Canada to the first author.     

DO INFANTS SHOW GENERALIZED IMITATION OF GESTURES? II. THE EFFECTS OF SKILLS TRAINING AND MULTIPLE EXEMPLAR MATCHING TRAINING

The determinants of generalized imitation of manual gestures were investigated in 1‐ to 2‐year‐old infants. Eleven infants were first trained eight baseline matching relations; then, four novel gestures that the infants did not match in probe trials were selected as target behaviors. Next, in a generalized imitation test in which matching responses to baseline models were intermittently reinforced, but matching responses to target models were not eligible for reinforcement, the infants matched baseline models but not the majority of their target behaviors. To ensure their failure to match the target behaviors was not due to motor constraints, the infants were trained, in a multiple‐baseline procedure, to produce the target responses under stimulus control that did not include an antecedent model of the target behavior. There was no evidence of generalized imitation in subsequent tests. When the infants were next trained to match each target behavior to criterion (tested in extinction) in a multiple‐baseline‐across‐behaviors procedure, only 2 infants continued to match all their targets in subsequent tests; the remaining infants matched only some of them. Seven infants were next given mixed matching training with the target behaviors to criterion (tested in extinction); they subsequently matched these targets without reinforcement when interspersed with trials on which matching responses to baseline models were intermittently reinforced. In repeat tests, administered at 3‐week intervals, these 7 children (and 2 that did not take part in mixed matching training) continued to match most of their target behaviors. The results support a trained matching account, but provide no evidence of generalized imitation, in 1‐ to 2‐year‐old infants.     

THEOLOGY,EVOLUTION, AND THE HUMAN MIND: HOW MUCH CAN BIOLOGY EXPLAIN?

Evolutionary biology contributes much to our present understanding of life, and it promises also to deepen our understanding of human intelligence, ethics, and even religion. For some scientific thinkers, however, Darwin's science seems so impressive that it now supplants theology altogether by providing the ultimate explanation of all manifestations of life, not only biologically but also metaphysically. By focusing on human intelligence as an emergent aspect of nature this essay examines the question of whether theology can still have an explanatory role to play alongside biology in attempts to understand mind.     

The stability and causal effects of task‐specific and generalized self‐efficacy in college1

This research investigated the stability and causal effects of task‐specific self‐efficacy and generalized self‐efficacy in college students. In Study 1, task‐specific self‐efficacy and generalized self‐efficacy scales were administered to university students (N = 237) on two occasions, with an interval of 2 months. In Study 2, task‐specific (care‐work) self‐efficacy and generalized self‐efficacy scales were administered to college students who were studying to be care workers (N = 49) on three occasions (before the first care‐work practicum, after the practicum, and 3 months later). The results of both studies indicated that generalized self‐efficacy was more stable than task‐specific self‐efficacy. In Study 1, both generalized self‐efficacy and task‐specific self‐efficacy affected each other in daily life. Study 2 examined the effects of an ego‐engaged experience (the first care‐work practicum) for task‐specific (care‐work) self‐efficacy and generalized self‐efficacy. The results indicated that changes in care‐work self‐efficacy did not affect generalized self‐efficacy.